In an LTE system, in order to improve spectrum efficiency, an intra-frequency networking manner is generally adopted, that is, a frequency is completely reused between neighboring cells. In the intra-frequency networking manner, strong interference exists between neighboring cells, which presents a challenge for uplink channel receiving of a base station. How to better suppress interference between neighboring cells to improve system performance is a hot spot of research in this field.
In the LTE system, four uplink channels are defined: a physical uplink shared channel (Physical Uplink Shared Channel, PUSCH), a physical uplink control channel (Physical Uplink Control Channel, PUCCH), a physical random access channel (Physical Random Access Channel, PRACH), and a sounding reference signal (Sounding Reference Signal, SRS). The PUSCH is used for uplink transmission of data, the PUCCH is used for uplink transmission of signaling, the PRACH is used for random access of a user equipment (User Equipment, UE), and the SRS is used for measuring uplink channel information. At present, many mature researches on suppression of interference among PUSCHs, PUCCHs, and SRSs of neighboring cells exist in the industry. For example, it is specified in a protocol that all of the foregoing three channels may be generated or scrambled by a physical cell identifier (Physical cell ID, PCI), and interference may be randomized by reasonably planning PCIs of neighboring cells. However, a few researches on suppression of interference between the PRACH and the three channels: the PUSCH, the PUCCH, and the SRS exist in the industry. A signal sent by a UE on the PRACH is called a preamble sequence (Preamble Sequence, Preamble). The preamble sequence is a Zadoff-Chu sequence (referred to as a ZC sequence), and its length is 839 points. The number of preamble sequences may be 838. The preamble sequence is also called a root sequence (Root Sequence, RS). Different preamble sequences are decided by different root sequence indexes (Root Sequence Index, RSI) and a value range of the RSI may be 1 to 838. In the protocol, according to characteristics of different RSs, RSIs may be rearranged. The rearranged RSIs become logic root sequence indexes (Logic Root Sequence Index, LRSI), where numbers of the logic root sequence indexes may be 0 to 837.
It is found through simulation that, when a PCI of a neighboring cell and an LRSI of a serving cell satisfy a relation: IN (PCI, LRSI)>1 (IN (PCI, LRSI) represents an interference coefficient of an SRS of the neighboring cell for detection of a PRACH of the serving cell, and 1 represents an interference coefficient threshold), the influence of the SRS of the neighboring cell on the detection of the PRACH of the serving cell is relatively large, which easily causes false detection of random access of a base station, thereby causing a false random access alarm.